Aspects of the present invention relate generally to the field of integrated circuit design, and more specifically to version management for Fluid Guard Ring PCells implemented in a design.
Integrated circuit (IC) design is increasingly complex, sometimes involving millions of elements, shapes or geometries, and may be facilitated with an electronic design automation (EDA) tool that allows a designer to interactively position (“place”) and connect (“route”) various shapes on the circuit. As part of the process of physical design, the EDA tool creates a circuit layout containing the physical locations and dimensions of the circuit's components, interconnections, and various layers from the original design that may then be fabricated, creating the IC. The designed IC is eventually fabricated by transferring or printing the circuit layout to a semiconductor substrate in a series of layers that collectively will form the features that constitute the devices that make up the components of the integrated circuit.
During the process of physical design of the IC, guard rings are often added to enclose one or more devices (e.g. transistors) in the layout. The added guard rings protect the enclosed device(s), for example against a latchup problem or from external noise. In some systems, the added guard rings are implemented in the EDA tool as fluid PCells. PCells that provide advanced creation and editing capabilities to the IC designer may be considered fluid PCells. More specifically, fluid guard rings are PCell devices that include the PCell formal parameters as well as Component Description Format (CDF) parameters. A fluid guard ring PCell device definition will be stored and accessible through the technology file of the design library.
However, certain updates or changes to fluid guard ring source code in the EDA tool, including updates, new feature support and bug fixes, can alter the footprint of an instance of a fluid guard ring PCell in a design. For example, when evaluating or testing the design using different source code releases, the geometry of the fluid guard ring can change. Then a design that was previously tested and qualified with an earlier version of the source code may need to be retested and re-qualified under the new release. Because of this uncertainty, IC designers often avoid updating the fluid guard ring source code to the newest release of the EDA tool.
Accordingly, there is a need in the art for a system that preserves the geometries of fluid PCells across different code versions.